package com.lb.algorithm;

import java.util.Arrays;
import java.util.HashMap;
import java.util.Map;

/**
 * @Author: zhangjun
 * @Date: 2020/5/28 19:39
 * @Description:给定一个整数数组 nums 和一个目标值 target，请你在该数组中找出和为目标值的那 两个 整数，并返回他们的数组下标。
 *
 * 你可以假设每种输入只会对应一个答案。但是，数组中同一个元素不能使用两遍。
 * 示例:
 *
 * 给定 nums = [2, 7, 11, 15], target = 9
 *
 * 因为 nums[0] + nums[1] = 2 + 7 = 9
 * 所以返回 [0, 1]
 */
public class TwoSum {
    public static int[] twoSum(int[] nums, int target) {
        int[] result = new int[2];
        /*outer:for (int i=0;i<nums.length;i++) {
            for (int j=i;j<nums.length;j++) {
                if (nums[i] + nums[j] == target) {
                    result[0] = i;
                    result[1] = j;
                    break outer;
                }
            }
        }*/

        Map<Integer, Integer> map = new HashMap<>();
        for (int i=0;i<nums.length;i++) {
            int diff = target - nums[i];
            if (map.get(diff) != null) {
                result[0] = map.get(diff);
                result[1] = i;
                break;
            }
            map.put(nums[i],i);
        }
        return result;
    }

    public static void main(String[] args) {

        int target = 10;
        int[] nums = {1, 3, 4, 6, 10};
        int[] result = twoSum(nums, target);
        long start = System.currentTimeMillis();
        System.out.println(Arrays.toString(result));
        long end = System.currentTimeMillis();
        System.out.printf("耗时：{%s}",end - start);
    }
}